Manufacturers and users of both voice and data communication systems have been very interested in optical fibers as a transmission medium. The advantages of fibers over other kinds of transmission media are well known. The potential bandwidth (or message carrying capacity) of optical fibers is extremely high. Systems using optical cables are resistant to electromagnetic interference which sometimes plagues systems having electrical cables. Moreover, optical cable systems are considered somewhat more secure than electrical cable systems since it is more difficult for unauthorized personnel to tap or access a fiber optic cable without being detected.
Problems have been encountered, however, in transferring fiber optic technology from the readily controlled environment of research and development facilities to the often not-so-readily controlled environment of the commercial world. One of these problems is that the high levels of system performance in a research and development environment can be attributed, at least in part, to the fact that a system is normally assembled by highly motivated, highly trained technical personnel. Such personnel are normally quite careful when handling cables and attaching connectors to minimize energy losses at connector-to-connector or connector-to-device interfaces.
The same system which performs well in a research and development environment may prove totally unacceptable in a commercial environment. Commercially available connectors, while varying in many respects, require that an in-the-wall or transmission fiber extend completely through the connector with the end of the fiber providing the optical interface between that connector and another connector or device. To minimize losses at such an interface, the end of the fiber must be carefully cut and polished. This can be achieved without substantial difficulty in a research and development environment.
In a commercial environment, however, a cable may be prepared and connectors may be mounted by personnel who lack the motivation or the training required to properly carry out such a job. If the optical fiber is not prepared correctly or the connector is not mounted correctly, the losses at the connector can be unacceptably high. With commercially available connectors, the only alternative in such a situation is to remove the old connector by sacrificing a length of cable and repeat the entire process of mounting a new connector. Repeated installation attempts can shorten the in-the-wall cable to the extent that the entire cable has to be replaced. To avoid this, the alternative has been to provide a great deal of excess cable at each outlet to allow the repeated sacrifices that might be necessary.
U.S. Pat. No. 4,220,394 represents a partial solution to the problems inherent in commercially available connectors. In the fiber optic connector disclosed in that patent, the connector body includes a short length of a permanently retained fiber. This short length of fiber can be fusion welded to the fiber in a transmission cable through the use of an oxyhydrogen micro-blowpipe. The problem with the connector proposed by this patent is that any failure to achieve satisfactory losses upon first installation of the connector can be remedied only by either breaking the weld formed within the connector or by cutting the cable at a point beyond the connector. In either event, a considerable length of the tranmission cable is sacrificed before a new or reworked connector can be mounted on the transmission cable.